diff options
author | shyouhei <shyouhei@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2018-11-15 05:10:40 +0000 |
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committer | shyouhei <shyouhei@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2018-11-15 05:10:40 +0000 |
commit | 2212c1dc165fa4251ff5085eec768daf3a0f69e5 (patch) | |
tree | 4ba6d9248c174442e5614e90e3e92a484807a9be /bignum.c | |
parent | 42d797d8e951fd99c071e75d31c942b6e0b5f201 (diff) |
bignum.c: ee should be signed
In C, signed + unsigned of the same size results in unsigned (cf:
ISO/IEC 9899:1990 section 6.2.1.5). However `num` is signed here.
Which means the addition must be done in signed.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65734 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'bignum.c')
-rw-r--r-- | bignum.c | 7 |
1 files changed, 4 insertions, 3 deletions
@@ -1511,15 +1511,16 @@ bigdivrem_mulsub(BDIGIT *zds, size_t zn, BDIGIT x, const BDIGIT *yds, size_t yn) i = 0; do { - BDIGIT_DBL ee; + BDIGIT_DBL_SIGNED ee; t2 += (BDIGIT_DBL)yds[i] * x; ee = num - BIGLO(t2); - num = (BDIGIT_DBL)zds[i] + ee; + num = (BDIGIT_DBL_SIGNED)zds[i] + ee; if (ee) zds[i] = BIGLO(num); num = BIGDN(num); t2 = BIGDN(t2); } while (++i < yn); - num += zds[i] - t2; /* borrow from high digit; don't update */ + num -= (BDIGIT_DBL_SIGNED)t2; + num += (BDIGIT_DBL_SIGNED)zds[yn]; /* borrow from high digit; don't update */ return num; } |